Antibacterial fabrics are widely used for production of outdoor clothes, under-wear, bed-linen, and bandages. Antimicrobial resistance is very important in textile materials, having effects amongst others on comfort for the wearer. The deposition of metal oxides known to possess antimicrobial activity, namely ZnO, MgO and CuO, can significantly extent the applications of textile fabrics and prolong the period of their use.
Zinc oxide has been recognized as a mild antimicrobial agent, non toxic wound healing agent, and sunscreen agent. Because it reflects both UVA and UVB rays, zinc oxide can be used in ointments, creams and lotions to protect against sunburn and other damage to the skin caused by ultraviolet lights [Godfrey H. R. Alternative Therapy Health Medicine, 7 (2001) 49]. At the same time ZnO is an inorganic oxide stable against temperatures encountered in normal textile use, contributing to its long functional lifetime without color change or oxidation. The antibacterial properties of MgO and CuO nanoparticles were also demonstrated [Controllable preparation of Nano-MgO and investigation of its bactericidal properties. Huang L., Li D. Q, Lin Y. J., Wei M., Evans D. G., Duan X. L. Inorganic Biochemistry, 99 (2005) 986, and Antibacterial Vermiculite Nano-Material. Li B., Yu S., Hwang J. Y., Shi S. Journal of Minerals & Materials Characterization & Engineering, 1 (2002) 61].
An antimicrobial formulation containing ZnO powder, binding agent, and dispersing agent was used to protect cotton and cotton-polyester fabrics [“Microbial Detection, Surface Morphology, and Thermal Stability of Cotton and Cotton/Polyester Fabrics Treated with Antimicrobial Formulations by a Radiation Method”. Zohby M. H., Kareem H. A., El-Naggar A. M., Hassan, M. S., J. Appl. Polym. Sci. 89 (2003) 2604] This formulation was applied to fabrics under high energy radiation of Co-60 γ or electron beam irradiation and then subjected for fixation by thermal treatment. A superior antimicrobial finish was achieved with cotton fabrics containing 2 wt % ZnO and with cotton-polyester fabrics containing 1 wt % ZnO. The particle size of ZnO in these samples according to SEM measurement was 3-5 μm. In spite of good antimicrobial activity, the disadvantages of this method are the use of additional binding and dispersing agent, and requirements of high energy radiation and an additional stage of thermal curing. It was also reported that ZnO-soluble starch nanocomposite was impregnated onto cotton fabrics to impart antibacterial and UV-protection functions with ZnO concentration 0.6-0.8 wt % [Functional finishing of cotton fabrics using zinc oxide-soluble starch nanocomposites. Vigneshwaran N., Kumar S., Kathe A. A., Varadarajan P., Prasad V., Nanotechnology 17 (2006) 5087]. The particle size of ZnO in zinc oxide-starch composition was reported as 38 nm. However, in this work the special stabilizing agent, namely, acrylic binder is used which should undergo the additional stage of polymerization at 140° C.
Improved methods of producing metal oxide nanoparticles and coating them onto surfaces is still a long felt need.